Kyle, most people (including anyone at Neumann) don't hear any such difference, and there's no design intention nor physical reason for there to be any sonic difference between a KM 140 and a KM 184--especially anything as range-specific as a "difference in the low end."
I'm not doubting that you heard whatever you heard, but it's not anything that generally holds true for those two models. If you have a chance to recreate your experiment some time with other microphones of the same two models, I urge you to do so and let us know whether your impression is still the same, particularly if you aren't in the position of knowing which one is which until you've made up your mind as to which one has which kind of bass.
The only essential difference is that the KM 140 uses an active capsule arrangement with the FET first stage located in the (separable) capsule unit. But when you attach the "passive" capsules of the KM 18x series to their bodies (the KM 183/184/185 circuitry is all identical), the distance to the FET is about the same so even stray capacitance, etc., are just about the same in the two models.
As someone else mentioned there have been two generations of KM 184 circuitry, but their gain (and thus the sensitivity of the complete microphone), maximum SPL and frequency response are absolutely identical. The KM 140 in turn is identical to both generations of KM 184 in those same respects. The sole outward difference between the two generations of KM 184 is the equivalent noise level, which was reduced by 3 dB in about 2001, while the phantom power requirement increased correspondingly from 2.3 mA to 3.2 mA per microphone.
--best regards
Topic: Neumann 140 vs Neumann 84i (Read 10662 times)